Probing n-propanol electrochemical oxidation on bimetallic PtRh codeposited electrodes

The adsorption and reaction of n-propanol was investigated using in situ Fourier transform IR spectroscopy and on-line differential electrochemical mass spectrometry on electrodeposited Pt, Rh, and PtRh with different compositions. It has been observed that the bimetallic electrodes were more active than pure platinum below 0.9 V. The pure rhodium electrode was practically inactive. Differences in product yield show that platinum is more active than the bimetallic electrodes for propionic acid formation, but the bimetallic electrodes show higher activity for CO2 and propanal production. The electrochemical reduction of the strongly adsorbed intermediates on pure platinum and on the two bimetallic electrodes gave products with 1, 2, and 3 carbons, while the pure rhodium electrode produced only methane. The degree of coverage by the irreversibly adsorbed species is about ten times higher on platinum than on the bimetallic electrodes or rhodium, showing that on the bimetallic electrodes the intermediates are not as strongly adsorbed as on pure platinum. (C) 2003 The Electrochemical Society.